Burst disks are employed in many pressurized fluid systems to prevent dangerous over-pressurization conditions from existing in the systems. In the event a pressurizable chamber to which a burst disk assembly is mounted becomes overpressurized, safety concerns require that it be immediately vented to reduce the pressure. This prevents the chamber from exploding. Such venting of high pressure fluid must be accomplished in a safe manner. The burst disks are typically the weakest structural components in the system. This is so that the likely pressure-induced rupture location in the system is limited to the burst disk, and the burst disk is generally positioned where people and surroundings are not likely to be injured by the rupturing of the burst disk. People and equipment must be protected from the jet of high pressure fluid, and from fragments of the burst disk. Also, the reaction force of the escaping jet of fluid must be prevented from turning the container it is escaping from into an uncontrolled missile.
Conventional pressure relief devices that include burst disks are generally designed with two or four vent holes drilled into a burst disk mounting plug which is secured to the pressurized fluid system at an attachment point. See, for example, U.S. Pat. No. 4,590,957, the disclosure of which is hereby incorporated by reference as if fully set forth herein. There is typically a portion of the mounting plug that remains exposed to the ambient environment at a distance from the attachment point. That distant exposed portion is generally referred to herein as the “head” of the mounting plug. The vent holes are generally formed by cross-drilling bores in a radial direction generally between the head and the attachment point of the mounting plug. The cross-drilled vent holes are drilled to intersect a central axially extending bore. The cross-drilled vent holes and the axial bore tend to weaken the attachment of the body of the mounting plug to the head. If the head breaks off in a disk rupture episode it becomes a missile.
Putting the radially extending vent holes near the bottom of the threaded plug, below the threads, ensures that the part of the body of the plug that is weakened by cross-drilling and boring will not break off and become a loose missile. Safety is thus enhanced. Burst disks are provided for purposes of safety, to control as much as possible an inherently unsafe situation where an over-pressurized condition exists in a pressurized fluid system. Improvements in burst disks that enhance safety are eagerly sought by those skilled in this art.
Pressure relief devices with a burst disks and a tortuous fluid flow path are known in the art. See, for example, U.S. Pat. No. 4,219,040, the disclosure of which is hereby incorporated by reference as if fully set forth herein. However, the plurality of vent ports formed in the cap can severely weaken the cap, which again presents the potential for portions of the assembly to break loose and become one or more projectiles in a disk rupture episode.
Hand-held pressurized fluid systems, such as those used with devices like paintball markers, present an additional safety concern with respect to overpressure venting. U.S. Pat. No. 7,051,751, the disclosure of which is hereby incorporated by reference as if fully set forth herein, illustrates in FIGS. 2 and 4 an example of a device in which the full force of the escaping fluid would be oriented in a single direction. Venting all of the pressure in the same direction generates a thrust which can turn the entire system into a projectile. For this reason, a preferable design is generally one that disperses the force of the escaping fluid in multiple directions, particularly directions which in combination result in near-zero net thrust on the hand-held device.
There exists a need for an inexpensive burst disk assembly with a low profile that significantly reduces the risk of structural failure and escaping burst disk fragments upon the rupturing of the burst disk. Just as important for some applications, the same burst disk assembly should disperse escaping pressurized fluid in multiple directions so as to avoid unidirectional thrust that can turn the pressurized system into a missile.